/*
 * Copyright 2002-2014 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package org.springframework.security.messaging.access.expression;

import org.springframework.expression.Expression;
import org.springframework.messaging.Message;
import org.springframework.security.access.ConfigAttribute;
import org.springframework.util.Assert;

/**
 * Simple expression configuration attribute for use in {@link Message}  authorizations.
 *
 * @since 4.0
 * @author Rob Winch
 */
@SuppressWarnings("serial")
class MessageExpressionConfigAttribute implements ConfigAttribute {
    private final Expression authorizeExpression;

    /**
     * Creates a new instance
     *
     * @param authorizeExpression the {@link Expression} to use. Cannot be null
     */
    public MessageExpressionConfigAttribute(Expression authorizeExpression) {
        Assert.notNull(authorizeExpression, "authorizeExpression cannot be null");

        this.authorizeExpression = authorizeExpression;
    }

    Expression getAuthorizeExpression() {
        return authorizeExpression;
    }

    public String getAttribute() {
        return null;
    }

    @Override
    public String toString() {
        return authorizeExpression.getExpressionString();
    }
}
